A relation between heat transferred and energy loss, for turbulent flow. In different tube arrangements, is made. The conditions are determined which decide the dimensions and velocities for a heat exchanger. Also, a ...A relation between heat transferred and energy loss, for turbulent flow. In different tube arrangements, is made. The conditions are determined which decide the dimensions and velocities for a heat exchanger. Also, a reference to the economic dimensioning of heat exchangers is presented. In this study, the conditions which a heat exchanger must satisfy represent the best balance between the amounts of material employed. The investigation is restricted to the case of turbulent flow.展开更多
Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utili...Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utilizing the reactive power capability of PV inverters to mitigate voltage deviations is being promoted.In recent years,droop control of inverter-based distributed energy resources has emerged as an essential tool for use in this study.The participation of PV systems in voltage regulation and its coordination with existing controllers,such as on-load tap changers,is paramount for controlling the voltage within specified limits.In this work,control strategies are presented that can be coordinated with the existing controls in a distributed manner.The effectiveness of the proposed method was demonstrated through simulation results on a distribution system.展开更多
The Hainan FTP is a game changer and those who seize the opportunities it offers early will reap substantial benefits.AS it provides a vital new model for China’sinternational trade and logistics,theHainan Free Trade...The Hainan FTP is a game changer and those who seize the opportunities it offers early will reap substantial benefits.AS it provides a vital new model for China’sinternational trade and logistics,theHainan Free Trade Port(Hainan FTP)stands out from similar opening-up initiatives.展开更多
The Hainan FTP is a game changer,and those who seize the opportunities it offers early will be in an advantageous position As it provides a vital new model for China’s international trade and logistics,the Hainan Fre...The Hainan FTP is a game changer,and those who seize the opportunities it offers early will be in an advantageous position As it provides a vital new model for China’s international trade and logistics,the Hainan Free Trade Port(FTP)stands out among similar opening-up initiatives.展开更多
As one of the key components of a UHV converter transformer,the suitable switching condition of the vacuum onload tap changer(OLTC)is essential for the stability of the power system.It is highly desirable to interpret...As one of the key components of a UHV converter transformer,the suitable switching condition of the vacuum onload tap changer(OLTC)is essential for the stability of the power system.It is highly desirable to interpret OLTC’s switching procedure to assess OLTC’s switching condition.However,such work can’t be solved by vibration analysis alone.Therefore,this paper proposes an innovative electromechanical comprehensive analysis method.First,a joint motor drive current,vibration,and electromagnetic signals online monitoring system is established and deployed in a VRG type OLTC in±800 kV converter station.Second,independent component analysis(ICA),dynamic time warping(DTW),and wavelet transform(WT)are used for processing motor current,UHFCT,and vibration signals,respectively,to extract electromechanical pulses corresponding to OLTC’s contact actions.Third,the switching procedure of OLTC is revealed by comprehensively analyzing the corresponding time relationship between these extracted pulses,combined with OLTC’s timing sequence.The methodologies developed in this paper can help to interpret OLTC’s switching procedure for deeper and finer online condition assessment.展开更多
Teacher-retraining course design is considered to be a challenge not only to the course participants but to the course designers as well, especially, when the participants enrolled turn out to have dramatically differ...Teacher-retraining course design is considered to be a challenge not only to the course participants but to the course designers as well, especially, when the participants enrolled turn out to have dramatically different professional background and conditions. This article supports the idea that changes to the course design should be made straightaway in response to the trainees＇ specific needs. The context for rural school teacher retraining at Novosibirsk State Technical University in Russia illustrates reasons for making immediate changes necessary as the course progressed, and reaction to them. The article discusses a model for a teacher retraining course in which EFL improvement is the core element.展开更多
To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part...To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part of the machining center as a driving source.The static attributes of the automatic tool changer using the commercial code,ANSYS Workbench V12,were tried to interpret.And the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum design.The shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable improvements.It is possible to obtain an optimized model in which the maximum deformation,maximum stress,and mass are reduced by 10.46%,12.89% and 9.26%,respectively,compared with those of the initial model.Also,the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.展开更多
Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current(DC)power adjustment.Based on a converter steady-state model and a DC power model,the control angle constraints ...Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current(DC)power adjustment.Based on a converter steady-state model and a DC power model,the control angle constraints of a converter valve are relaxed for power regulation.In this paper,a flexible DC power control method based on a fixed tap changer position is proposed.The initial ratio of the converter transformer is optimized.The effects of the fixed-tap changer position control on the control angle,reactive power compensation,and commutation failure are analyzed.The new control method allows a DC system to operate at a large angle and increase the additional reactive power loss while improving the commutation security margin.Steady-state and electromagnetic transient simulations in the CIGRE test system verify the validity of the method proposed in this paper and the correctness of the analysis conclusions.展开更多
全球广播和媒体行业的盛会——NAB2016刚刚在美国拉斯维加斯落下帷幕。来自全世界的广播和媒体的从业者汇聚在这里,展示和交流最新的技术、产品和解决方案,共谋未来业务发展。索贝公司与SONY公司合作,向全球客户展示了基于HIVE的全新新...全球广播和媒体行业的盛会——NAB2016刚刚在美国拉斯维加斯落下帷幕。来自全世界的广播和媒体的从业者汇聚在这里,展示和交流最新的技术、产品和解决方案,共谋未来业务发展。索贝公司与SONY公司合作,向全球客户展示了基于HIVE的全新新闻制播系统Media Backbone HIVE,并一举摘取IABM Game Changer大奖!展开更多
How many electronics and electrical devices do you use daily? Cell phone, computer, TV, earphone, smartwatch, electronic toothbrush, relYigerator, washing machine, water heater, E-「eader, just to name a few. They'...How many electronics and electrical devices do you use daily? Cell phone, computer, TV, earphone, smartwatch, electronic toothbrush, relYigerator, washing machine, water heater, E-「eader, just to name a few. They've played a big rote in our Lives, sometimes a Life changer (cochlear implants, etc. for people with disabilities). New e-devices constantly emerge with the advance of technology, replacing the old ones, either broken 〇「stUL weU-functioning. Do you ever think of what happens to them after being dumped?展开更多
文摘A relation between heat transferred and energy loss, for turbulent flow. In different tube arrangements, is made. The conditions are determined which decide the dimensions and velocities for a heat exchanger. Also, a reference to the economic dimensioning of heat exchangers is presented. In this study, the conditions which a heat exchanger must satisfy represent the best balance between the amounts of material employed. The investigation is restricted to the case of turbulent flow.
基金by a project under the scheme entitled“Developing Policies&Adaptation Strategies to Climate Change in the Baltic Sea Region”(ASTRA),Project No.ASTRA6-4(2014-2020.4.01.16-0032).
文摘Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utilizing the reactive power capability of PV inverters to mitigate voltage deviations is being promoted.In recent years,droop control of inverter-based distributed energy resources has emerged as an essential tool for use in this study.The participation of PV systems in voltage regulation and its coordination with existing controllers,such as on-load tap changers,is paramount for controlling the voltage within specified limits.In this work,control strategies are presented that can be coordinated with the existing controls in a distributed manner.The effectiveness of the proposed method was demonstrated through simulation results on a distribution system.
文摘The Hainan FTP is a game changer and those who seize the opportunities it offers early will reap substantial benefits.AS it provides a vital new model for China’sinternational trade and logistics,theHainan Free Trade Port(Hainan FTP)stands out from similar opening-up initiatives.
文摘The Hainan FTP is a game changer,and those who seize the opportunities it offers early will be in an advantageous position As it provides a vital new model for China’s international trade and logistics,the Hainan Free Trade Port(FTP)stands out among similar opening-up initiatives.
基金supported by the Science and Technology Project of State Grid Corporation of China(NO.5500-202016076A-0-0-00).
文摘As one of the key components of a UHV converter transformer,the suitable switching condition of the vacuum onload tap changer(OLTC)is essential for the stability of the power system.It is highly desirable to interpret OLTC’s switching procedure to assess OLTC’s switching condition.However,such work can’t be solved by vibration analysis alone.Therefore,this paper proposes an innovative electromechanical comprehensive analysis method.First,a joint motor drive current,vibration,and electromagnetic signals online monitoring system is established and deployed in a VRG type OLTC in±800 kV converter station.Second,independent component analysis(ICA),dynamic time warping(DTW),and wavelet transform(WT)are used for processing motor current,UHFCT,and vibration signals,respectively,to extract electromechanical pulses corresponding to OLTC’s contact actions.Third,the switching procedure of OLTC is revealed by comprehensively analyzing the corresponding time relationship between these extracted pulses,combined with OLTC’s timing sequence.The methodologies developed in this paper can help to interpret OLTC’s switching procedure for deeper and finer online condition assessment.
文摘Teacher-retraining course design is considered to be a challenge not only to the course participants but to the course designers as well, especially, when the participants enrolled turn out to have dramatically different professional background and conditions. This article supports the idea that changes to the course design should be made straightaway in response to the trainees＇ specific needs. The context for rural school teacher retraining at Novosibirsk State Technical University in Russia illustrates reasons for making immediate changes necessary as the course progressed, and reaction to them. The article discusses a model for a teacher retraining course in which EFL improvement is the core element.
基金Work(RTI04-01-03) supported by Grant from Regional Technology Innovation Program of the Ministry of Knowledge Economy (MKE),Korea
文摘To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part of the machining center as a driving source.The static attributes of the automatic tool changer using the commercial code,ANSYS Workbench V12,were tried to interpret.And the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum design.The shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable improvements.It is possible to obtain an optimized model in which the maximum deformation,maximum stress,and mass are reduced by 10.46%,12.89% and 9.26%,respectively,compared with those of the initial model.Also,the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.
基金an independent research project from the Shandong Electric Power Research Institute,“Research on the control method of DC power under fixed converter transformer tap-changer position”(ZY-2020-01)Based on the achievement,a national invention patent(No.2020112240143)has been applied.
文摘Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current(DC)power adjustment.Based on a converter steady-state model and a DC power model,the control angle constraints of a converter valve are relaxed for power regulation.In this paper,a flexible DC power control method based on a fixed tap changer position is proposed.The initial ratio of the converter transformer is optimized.The effects of the fixed-tap changer position control on the control angle,reactive power compensation,and commutation failure are analyzed.The new control method allows a DC system to operate at a large angle and increase the additional reactive power loss while improving the commutation security margin.Steady-state and electromagnetic transient simulations in the CIGRE test system verify the validity of the method proposed in this paper and the correctness of the analysis conclusions.
文摘全球广播和媒体行业的盛会——NAB2016刚刚在美国拉斯维加斯落下帷幕。来自全世界的广播和媒体的从业者汇聚在这里,展示和交流最新的技术、产品和解决方案,共谋未来业务发展。索贝公司与SONY公司合作,向全球客户展示了基于HIVE的全新新闻制播系统Media Backbone HIVE,并一举摘取IABM Game Changer大奖!
文摘How many electronics and electrical devices do you use daily? Cell phone, computer, TV, earphone, smartwatch, electronic toothbrush, relYigerator, washing machine, water heater, E-「eader, just to name a few. They've played a big rote in our Lives, sometimes a Life changer (cochlear implants, etc. for people with disabilities). New e-devices constantly emerge with the advance of technology, replacing the old ones, either broken 〇「stUL weU-functioning. Do you ever think of what happens to them after being dumped?
